To specify an extra value to read, the caller must provide this, as well
as (optionally NULL)
appStorage pointer.

appStorage

void*

If this pointer is null, then the received value is stored in memory
managed by the NdbRecAttr
object. Otherwise, the received value is stored at the
location pointed to (and is still accessable using the
NdbRecAttr object).

Important

It is the caller's responsibility to ensure that
the following conditions are met:

appStorage points to
sufficient space to store any returned data.

Memory pointed to by
appStorage is not reused
or freed until after the
execute() call returns.